Effects of inedible, manipulable objects on captive bears

Bears in captivity often show abnormal behaviors such as stereotypies and periods of excessive inactivity. Most of the research aimed at reducing abnormal behaviors in bears has focused on feeding enrichment. However, the effects of feeding enrichment only seem to last as long as it takes a bear to consume the food. This study investigated the effects of inedible, manipulable objects on bears. Two polar bears (Ursus maritimus) received plastic floats. A sloth bear (Melursus ursinus) and a spectacled bear (Treniarctos ornatus) received plastic balls. During a 7-week period, polar bears nearly doubled their activity in the presence of toy floats, and the spectacled bear halved its pacing in the presence of toys. The sloth bear did not respond to the objects. These findings indicate that access to manipulable nonfood objects such as plastic toys can result in prolonged engagement in appetitive behaviors by polar bears.     

Individual Effects of Seasonal Changes,Visitor Density,and Concurrent Bear Behavior on Stereotypical Behaviors in Captive Polar Bears (Ursus maritimus)

Stereotypical behaviors in captive polar bears (Ursus maritimus) can be detrimental to their welfare. These behaviors can be reduced through enrichment programs but are often not completely eliminated, so identifying potential triggers is important. The present study investigated the influences of seasonal changes, visitor density, and concurrent bear activity on stereotypical behaviors exhibited by 3 captive polar bears at the Toronto Zoo. All bears exhibited these behaviors; however, individual differences were found in duration and form. The male exhibited less stereotypical behavior during spring, and the females exhibited less stereotypical behavior during winter. An increase in visitor density was associated with more stereotypical behavior in 1 female but less stereotypical behavior in the other 2 bears. All bears engaged in more stereotypical behaviors when the other bears were inactive, and 1 female engaged in more stereotypical behaviors when the other bears were out of sight. Further, when conspecifics were active, all bears engaged in less stereotypical behaviors. Given the variability among individual bears, future enrichment programs must be tailored to the needs of individuals to maximize efficacy.     

Phylogeny of the bears (Ursidae) based on nuclear and mitochondrial genes

The taxomic classification and phylogenetic relationships within the bear family remain argumentative subjects in recent years. Prior investigation has been concentrated on the application of different mitochondrial (mt) sequence data, herein we employ two nuclear single-copy gene segments, the partial exon 1 from gene encoding interphotoreceptor retinoid binding protein (IRBP) and the complete intron 1 from transthyretin (TTR) gene, in conjunction with previously published mt data, to clarify these enigmatic problems. The combined analyses of nuclear IRBP and TTR datasets not only corroborated prior hypotheses, positioning the spectacled bear most basally and grouping the brown and polar bear together but also provided new insights into the bear phylogeny, suggesting the sister-taxa association of sloth bear and sun bear with strong support. Analyses based on combination of nuclear and mt genes differed from nuclear analysis in recognizing the sloth bears as the earliest diverging species among the subfamily ursine representatives while the exact placement of the sun bear did not resolved. Asiatic and American black bears clustered as sister group in all analyses with moderate levels of bootstrap support and high posterior probabilities. Comparisons between the nuclear and mtDNA findings suggested that our combined nuclear dataset have the resolving power comparable to mtDNA dataset for the phylogenetic interpretation of the bear family. As can be seen from present study, the unanimous phylogeny for this recently derived family was still not produced and additional independent genetic markers were in need.     

Behavioral response of polar bears to aircraft activity on the northern coast of Alaska

The rapid loss of arctic sea ice is forcing a larger proportion of the Southern Beaufort Sea polar bear (Ursus maritimus) population to spend more time on land, increasing chances of negative interactions between people and bears. In the United States, the Marine Mammal Protection Act (MMPA) protects polar bears from incidental disturbance from human activities. For the remote and roadless areas of northern Alaska, USA, effective management of small aircraft activity is necessary to limit disturbance, but effects of overflights on polar bear behavior are largely unknown. During 2021 and 2022, we intentionally exposed polar bears (n = 115) to systematic aircraft activity (helicopter, fixed-wing) until we observed a disruption of behavior that qualified as a level B take response (e.g., abrupt change in activity or movement) under the MMPA. We used a Bayesian logistic regression to determine what factors influence and can be used to predict when a polar bear will exhibit a level B take response and estimate the probability of an aircraft eliciting a level B take response at different altitudes above the polar bear. Aircraft type, flight altitude, landscape (barrier islands vs. mainland), and bear behavior (active vs. inactive) upon initial aircraft encounter were all important predictors of take. Probability of take rapidly increased with a decrease in flight altitude starting at 450 m for helicopter and 300 m for fixed-wing aircraft. Active (e.g., standing, walking) polar bears on barrier-island landscapes were more likely to experience take than inactive (e.g., bedded) bears on mainland landscapes. Our findings can help with assessments and management plans by quantifying disturbance to polar bears from current and future human activity that involves aircraft use.     

Rapid radiation events in the family Ursidae indicated by likelihood phylogenetic estimation from multiple fragments of mtDNA.

The bear family (Ursidae) presents a number of phylogenetic ambiguities as the evolutionary relationships of the six youngest members (ursine bears) are largely unresolved. Recent mitochondrial DNA analyses have produced conflicting results with respect to the phylogeny of ursine bears. In an attempt to resolve these issues, we obtained 1916 nucleotides of mitochondrial DNA sequence data from six gene segments for all eight bear species and conducted maximum likelihood and maximum parsimony analyses on all fragments separately and combined. All six single-region gene trees gave different phylogenetic estimates; however, only for control region data was this significantly incongruent with the results from the combined data. The optimal phylogeny for the combined data set suggests that the giant panda is most basal followed by the spectacled bear. The sloth bear is the basal ursine bear, and there is weak support for a sister taxon relationship of the American and Asiatic black bears. The sun bear is sister taxon to the youngest clade containing brown bears and polar bears. Statistical analyses of alternate hypotheses revealed a lack of strong support for many of the relationships. We suggest that the difficulties surrounding the resolution of the evolutionary relationships of the Ursidae are linked to the existence of sequential rapid radiation events in bear evolution. Thus, unresolved branching orders during these time periods may represent an accurate representation of the evolutionary history of bear species.     

Phylogenetic Relationships of Bears (the Ursidae) Inferred from Mitochondrial DNA Sequences

The phylogenetic relationships among some bear species are still open questions. We present here mitochondrial DNA sequences of D-loop region, cytochrome b, 12S rRNA, tRNA^Pro, and tRNA^Thr genes from all bear species and the giant panda. A series of evolutionary trees with concordant topology has been derived based on the combined data set of all of the mitochondrial DNA sequences, which may have resolved the evolutionary relationships of all bear species: the ancestor of the spectacled bear diverged first, followed by the sloth bear; the brown bear and polar bear are sister taxa relative to the Asiatic black bear; the closest relative of the American black bear is the sun bear. Primers for forensic identification of the giant panda and bears are proposed. Analysis of these data, in combination with data from primates and antelopes, suggests that relative substitutional rates between different mitochondrial DNA regions may vary greatly among different taxa of the vertebrates.     

A Phylogeny of the Bears (Ursidae) Inferred from Complete Sequences of Three Mitochondrial Genes

Complete sequences of DNA are described for the cytochrome b, tRNA^Thrand tRNA^Progenes of mitochondria of four extant species of ursids and compared to sequences of four other species of ursids previously studied by us. Phylogenetic analyses indicate that the giant panda and the spectacled bear are the basal taxa of the ursid radiation. The ursines, a group which includes the sun bear, sloth bear, American black bear, Asiatic black bear, brown bear, and polar bear, experienced a rapid radiation during the mid Pliocene to early Pleistocene. The Asiatic black bear and American black bear are sister taxa. The brown bear and polar bear are the most recently derived of the ursines, with the polar bear originating from within a clade of brown bears during the Pleistocene. This paraphyletic association suggests that the rate of morphological evolution may be accelerated relative to that of molecular evolution when a new ecological niche is occupied. Calibration of the corrected average number of nucleotide differences per site with the fossil record indicates that transitions at third positions of codons in the ursid cytochrome b gene occur at a rate of approximately 6% per million years, which is considerably slower than comparable values reported for other species of mammal.     

MOLECULAR GENETIC-DISTANCE ESTIMATES AMONG THE URSIDAE AS INDICATED BY ONE- AND TWO-DIMENSIONAL PROTEIN ELECTROPHORESIS

Evolutionary relationships among eight species of Ursidae (including the giant panda) relative to two Procyonidae species (raccoon and red panda) were estimated based on the extent of electrophoretic variation of 289 radiolabelled fibroblast proteins resolved by two-dimensional gel electrophoresis and among 44 isozyme loci resolved by one-dimensional electrophoresis. Allelic differences among these species were converted to genetic distances, and phenetic trees were constructed. In addition, the electrophoretic data were coded as unit characters, and minimum-length trees were derived based on the Wagner method using maximum parsimony. Regardless of the tree-building method employed, the data sets agreed on the following branching sequence: between 22.4 and 32.3 million years (MY) ago, the ancestors of the procyonids and the ursids split into two lineages. Within 10 MY, the red panda split from the line that led to the raccoon. An ancestor of the giant panda split from the ursid line 18–22 MY ago, and the South American spectacled bear split from the line leading to ursine bears 10.5–15.0 MY B.P. A group of six closely related ursine bears (brown bear, polar bear, Asiatic black bear, Malayan sun bear, American black bear, and sloth bear) diverged from a common ancestor during the past 4–8 MY. Much of this ursine radiation was not resolved by our results, with the exception of a recent (2–3 MY B.P.) divergence of brown bear and polar bear. The topological concordance of the data sets from one- and two-dimensional electrophoresis supports the usefulness of these procedures for evolutionary inference and provides additional precision to the reconstruction of divergence nodes of this carnivore group.     

Environmental enrichment for zoo bears

The high incidence of stereotypic behaviors in zoo bears (van Keulen-Kromhout: International Zoo Yearbook 18:177–186, 1978) suggests that the environment of these animals lacks essential stimuli for guiding normal behavior. Three experiments investigated ways in which bear husbandry procedures can be altered to promote normal behavior. In experiments 1 and 2, honey-filled logs were given to a sloth (Melursus ursinus), American black (Ursus americanus), and brown bear (Ursus arctos) to determine 1) the role of food in stimulating investigatory behavior, 2) the rate of habituation to manipulable objects introduced into the exhibit, and 3) effects on locomotory behaviors. Results show specific and general habituation to the introduced objects that can be counteracted by refilling the logs with honey and by providing multiple logs in the exhibit. Investigatory activity directed toward honey-logs replaces pacing and walking in the sloth bear and is most effective in doing so when the log is novel. Experiment 3 examined the behavioral effects of feeding an American black bear in three different ways: 1) once daily in the den, 2) once daily with supplemental food from a mechanical feeder, and 3) once daily with food hidden in the exhibit in manipulatable objects. The latter method reduced stereotypic pacing from a median of 150 min/day to 20 min/day; the mechanical feeder method had no such effect. The results of a survey of 67 zoos concerning the diet and manner of feeding these three species of bears, as well as Asian black bears (Ursus thibetanus) are presented. Results are discussed with respect to the ways in which husbandry procedures can be improved to stimulate functional foraging and feeding behavior in confined bears.     

Can whisker spot patterns be used to identify individual polar bears?

Studies of population dynamics, movement patterns and animal behavior usually require identification of individuals. We evaluated the reliability of using whisker spot patterns to noninvasively identify individual polar bears Ursus maritimus . We obtained the locations of polar bear whisker spots from photographs taken in western Hudson Bay, tested the independence of spot locations, estimated the complexity of each spot pattern in terms of information and determined whether each whisker spot pattern was reliable from its information content. Of the 50 whisker spot patterns analyzed, 98% contained enough information to be reliable, and this result varied little among observers. Photographs taken <50 m from polar bears were most useful. Our results suggest that individual identification of polar bears in the field based on whisker spot pattern variations is reliable. Researchers studying polar bear behavior or estimating population parameters can benefit from this method if proximity to the bears is feasible.     

Effect of felid activity on zoo visitor interest

The extent to which the presence of zoo visitors influences animal behavior, and the ways in which animal activity influences visitor interest and perception, are of great interest to zoological parks. Visitors have been variously characterized as being enriching for zoo animals, as being stressors, and generally as influencing behavior in measurable ways. Most studies have focused on primates, and have assumed a “visitor effect” paradigm (i.e., visitors influence animal behavior). Here we present findings from a study of a nonprimate group (felids), and examine the “visitor attraction” model, which assumes that visitors are attracted to active animals. We assessed visitor interest and number at seven cat exhibits at the Brookfield Zoo during the spring and summer of 2002. Data were collected during 1‐min scans of each exhibit at 10‐min intervals. The results indicate that visitor presence per se did not influence cat activity, and that visitor interest was generally greater when cats were active. Various species differences may be explained by visitor familiarity with the species, variations in exhibit design, and species‐specific activity budgets. We conclude that the visitor attraction model may be more appropriate for taxa, such as large cats, that tend naturally to be largely inactive and to respond little (if at all) to visitor disturbances or efforts to engage. The relationship must be viewed as bidirectional: visitors influence animal behavior, and animal behavior influences visitor interest. However, the strength and primary direction of this relationship is likely taxon‐specific. We suggest that a visitor attraction model may be more appropriate not only for felids, but for other taxa with similar behavioral patterns and responses as well. Zoo Biol 22:587–599, 2003. © 2003 Wiley‐Liss, Inc.     

Variation in visitor perceptions of a polar bear enclosure based on the presence of natural vs. un-natural enrichment items

A debate exists among modern zoo staff as to whether or not the addition of un-naturalistic enrichment takes away from, or even defeats, the educational messages designers are trying to incorporate in naturalistic exhibits. A visitor study was conducted at the Central Park Zoo's polar bear exhibit in order to determine whether or not the type of enrichment in an enclosure actually alters guest perceptions. Visitors were exposed to one of two enrichment treatments in the bear enclosure: Naturalistic or Un-naturalistic. The results of this study suggest that enrichment type did not alter the perceptions of visitors. However, it did identify some of the different ways adults and youths perceive animals and zoos. Additionally, the study highlighted the varying perceptions individuals have of the concept of polar bears vs. their perceptions of the captive individuals at the Central Park Zoo. Implications for enrichment usage and exhibit design are discussed. Zoo Biol 28:292–306, 2009. © 2008 Wiley-Liss, Inc.     

Fine‐scale ecological and anthropogenic variables predict the habitat use and detectability of sloth bears in the Churia habitat of east Nepal

Once widespread throughout the tropical forests of the Indian Subcontinent, the sloth bears have suffered a rapid range collapse and local extirpations in the recent decades. A significant portion of their current distribution range is situated outside of the protected areas (PAs). These unprotected sloth bear populations are under tremendous human pressures, but little is known about the patterns and determinants of their occurrence in most of these regions. The situation is more prevalent in Nepal where virtually no systematic information is available for sloth bears living outside of the PAs. We undertook a spatially replicated sign survey‐based single‐season occupancy study intending to overcome this information gap for the sloth bear populations residing in the Trijuga forest of southeast Nepal. Sloth bear sign detection histories and field‐based covariates data were collected between 2 October and 3 December 2020 at the 74 randomly chosen 4‐km² grid cells. From our results, the model‐averaged site use probability (ψ ± SE) was estimated to be 0.432 ± 0.039, which is a 13% increase from the naïve estimate (0.297) not accounting for imperfect detections of sloth bear signs. The presence of termite mound and the distance to the nearest water source were the most important variables affecting the habitat use probability of sloth bears. The average site‐level detectability (p ± SE) of sloth bear signs was estimated to be 0.195 ± 0.003 and was significantly determined by the index of human disturbances. We recommend considering the importance of fine‐scale ecological and anthropogenic factors in predicting the sloth bear‐habitat relationships across their range in the Churia habitat of Nepal, and more specifically in the unprotected areas.     

Habitat occupancy of sloth bear Melursus ursinus in Chitwan National Park,Nepal

Mammals have experienced a massive decline in their populations and geographic ranges worldwide. The sloth bear, Melursus ursinus (Shaw, 1791), is one of many species facing conservation threats. Despite being endangered in Nepal, decades of inattention to the situation have hindered their conservation and management. We assessed the distribution and patterns of habitat use by sloth bears in Chitwan National Park (CNP), Nepal. We conducted sign surveys from March to June, 2020, in 4 × 4 km grids (n = 45). We collected detection/non‐detection data along a 4‐km trail that was divided into 20 continuous segments of 200 m each. We obtained environmental, ecological, and anthropogenic covariates to understand determinants of sloth bear habitat occupancy. The data were analyzed using the single‐species single‐season occupancy method, with a spatially correlated detection. Using repeated observations, these models accounted for the imperfect detectability of the species to provide robust estimates of habitat occupancy. The model‐averaged occupancy estimate for the sloth bear was 69% and the detection probability was 0.25. The probability of habitat occupancy by sloth bears increased with the presence of termites and fruits and in rugged, dry, open, undisturbed habitats. Our results indicate that the sloth bear is elusive, functionally unique, and widespread in CNP. Future conservation interventions and action plans aimed at sloth bear management must adequately consider their habitat requirements.     

Hematology of sloth bears (Melursus ursinus ursinus) from two locations in India

Standard hematology parameters were determined for 122 sloth bears (Melursus ursinus ursinus) at the Sur Sarovar Bird Sanctuary, Uttar Pradesh, India (27 degrees 0'N; 77 degrees 45'E), and the Bannerghatta Biological Park, Karnataka, India (12 degrees 48'N; 77 degrees 34'E) from March 2003 to July 2006. These two native sloth bear habitats have different climatic conditions and provided an opportunity to examine the effect of climate on the physiologic hematology values of these bears. We primarily analyzed the influence of age, sex, season, and body weight on the different hematology parameters. Several values were significantly different in sloth bear cubs (1 yr). The cubs had a lower erythrocyte count, hemoglobin concentration, packed cell volume (PCV), and mean cell hemoglobin (MCV) values when compared to adult and subadult bears. The cubs also had higher leukocyte counts, due to higher circulating neutrophils, as compared to adult and subadult bears. Within subadult and adult bears, we also identified a sexual dimorphic difference in leukocyte count in adult and subadult bears, wherein female bears had higher counts than males. This difference was the result of a significantly higher number of circulating neutrophils in female bears. Platelet counts were also higher in females as compared to males. On comparing different seasons, leukocyte counts were higher in winter as compared to the summer and monsoon seasons. When compared based on location, erythrocyte counts were higher in subadult and adult bears at Bannerghatta, which was at a higher altitude than Sur Sarovar. Within subadult and adult bears, we did not find any significant influence of age or body weight on the different hematologic parameters. In this study we have obtained mean hematologic values for sloth bears in their native habitat to serve as a reference for this species. This report will be useful to develop and evaluate health profiles of sloth bears under various ecological conditions.     

Using stage‐based system dynamics modeling for demographic management of captive populations

Management of captive populations relies on a complex synthesis of genetic and demographic analyses to guide populations toward sustainability. Demographic analyses of captive populations currently utilize age‐based matrix projections to predict a population's trajectory. An alternate approach is to use a stage‐based, system dynamics model for captive systems. Such models can more easily incorporate complex captive systems in which population dynamics are dependent on a combination of management and a species' biology. By linking these two areas, population managers can gain a more accurate understanding of how management decisions impact captive populations and which aspects of a species' demography should be of special concern in the future. We present a general stage‐based system dynamics model that has been developed for use with captive populations. The utility of the model is then illustrated by applying it to three captive bear populations: spectacled bears (Tremarctos ornatus), sloth bears (Melursus ursinus), and sun bears (Helarctos malayanus). Zoo Biol 22:45–64, 2003. © 2003 Wiley‐Liss, Inc.     

Visitor reaction to pacing behavior: influence on the perception of animal care and interest in supporting zoological institutions

Many publications within the field of zoo animal welfare have stated the importance of decreasing stereotypic behavior (e.g., pacing) to help ensure a positive visitor experience. The idea behind these statements is that visitors want to see animals engaged in natural behavior. Additionally, it is thought that watching an animal exhibit species-appropriate behavior could help increase a visitor's connection to wildlife and ultimately their interest in conservation. However, until recently, no information was available to validate such statements. The purpose of this research was to examine people's reaction to viewing an animal engaged in pacing behavior. Participants were randomly selected to fill out a survey after watching a short video of either a tiger pacing or resting (control). Results indicate that having viewed a tiger pacing significantly decreases people's perception of the level of care animals receive at that facility. In addition, people's interest in supporting zoos decreased as a result of viewing this behavior. Results are discussed from an animal welfare, business, and conservation perspective.     

Challenges of Large Carnivore Conservation: Sloth Bear Attacks in Sri Lanka

Sloth bear (Melursus ursinus) attacks in Sri Lanka present a major challenge to their conservation as human populations grow and compete with bears for space and resources. Bear attacks on humans predominantly affect the rural poor and seem to be increasing in frequency. In 2004, we conducted the first island-wide survey of bear attacks in Sri Lanka. Our main goals were to 1) describe where and when attacks occurred, 2) describe the characteristics and outcome of bear attacks, and 3) evaluate the influence of human group size on the severity of bear attacks. We interviewed 271 individuals attacked by sloth bears between 1938 and 2004. Sloth bears rarely entered village compounds, damaged property, or raided crops; conflicts predominantly involved attacks on people in forests. Most sloth bear attacks took place during daylight hours (0900-1600 h) in the dry season, when humans were likely to engage in forest activities such as honey gathering. Most attacks (80 %) occurred when humans and bears surprised each other at close proximity (<10 m). Most (84 %) victims carried a weapon but 55 % said the attack was too sudden to effectively use the weapon in self-defense. Human injuries included lacerations and puncture wounds, broken limbs, skull fractures, and the loss of scalps, eyes, or other parts of the face. Almost all major injuries resulted from bites. In 61 attacks bears were wounded and in 39 attacks bears were killed. The severity of human injuries depended on human group size; solitary humans experienced more severe injuries than expected, suggesting that the presence of other humans may moderate the bear’s aggression and motivate it to flee. Widespread fear of sloth bears poses a significant challenge to modifying ineffective human responses to bear encounters (e.g., fleeing). Conservation outreach could emphasize that greater human safety may be achieved from remaining in groups and using extreme caution around thickets and rock outcrops likely to be used by bears.     

Seed Dispersal by the Sloth Bear (Melursus ursinus) in South India1

Previous studies have shown that sloth bears are mainly myrmecophagous, but in this study, 39 and 83 percent (wet and dry season, respectively) of scats surveyed in South India contained fruits. Seeds from three of six plant species collected from scats germinated faster than seeds not passing through bears; germination percentage was not higher in any of the six species. These results suggest that the sloth bear may play an important role in the population dynamics of fleshy‐fruited species of the region.     

The acute physiological response of polar bears to helicopter capture

Many wildlife species are live captured, sampled, and released; for polar bears (Ursus maritimus) capture often requires chemical immobilization via helicopter darting. Polar bears reduce their activity for approximately 4 days after capture, likely reflecting stress recovery. To better understand this stress, we quantified polar bear activity (via collar-mounted accelerometers) and body temperature (via loggers in the body core [T_abd] and periphery [T_per]) during 2–6 months of natural behavior, and during helicopter recapture and immobilization. Recapture induced bouts of peak activity higher than those that occurred during natural behavior for 2 of 5 bears, greater peak T_per for 3 of 6 bears, and greater peak T_abd for 1 of 6 bears. High body temperature (>39.0°C) occurred in T_per for 3 of 6 individuals during recapture and 6 of 6 individuals during natural behavior, and in T_abd for 2 of 6 individuals during recapture and 3 of 6 individuals during natural behavior. Measurements of T_abd and T_per correlated with rectal temperatures measured after immobilization, supporting the use of rectal temperatures for monitoring bear response to capture. Using a larger dataset (n = 66 captures), modeling of blood biochemistry revealed that maximum ambient temperature during recapture was associated with a stress leukogram (7–26% decline in percent lymphocytes, 12–21% increase in percent neutrophils) and maximum duration of helicopter operations had a similar but smaller effect. We conclude that polar bear activity and body temperature during helicopter capture are similar to that which occurs during the most intense events of natural behavior; high body temperature, especially in warm capture conditions, is a key concern; additional study of stress leukograms in polar bears is needed; and additional data collection regarding capture operations would be useful.